Cardiovascular disease (CVD) continues to be the leading cause of death in the U.S. Of the various conditions that fall under the umbrella of cardiovascular disease, myocardial infarction (MI), known more commonly as a heart attack, is directly responsible for a significant number of the deaths attributed to CVD, and is a contributing factor in mortality attributed to other forms of CVD. With 1.2 million new or recurrent cases of MI reported every year, more than a third of which result in death, improving on current treatments and developing new, more effective treatments for MI are top priorities. Cardiac researchers have identified many proteins that that protect the heart against I/R injury. However, translation of this knowledge to the clinical setting is hampered by our inability to modify proteins and their expression levels in vivo without transgenesis. Alpha B- Crystallin (1BC) is a protein that has been identified as having robust cardioprotective effects in various models which mimic myocardial infarction. Furthermore, modifications have been identified which enhance the protective effects of the protein. We have taken the first steps in developing a system to deliver 1BC proteins to cells and tissue without using transfection, viral transfer or trangenesis. This unique system utilizes the properties of cell penetrating peptides (CPP) which have the ability to move themselves and cargo across cell membranes. We have devised a system that creates a reversible linkage between the 1CB protein and the CPP allowing for the delivery of 1BC into cells. Once inside the cell, the linkage between the two molecules is cleaved, freeing the 1BC protein within the cell. We have demonstrated that this system works effectively in vitro and can deliver 1BC to cells in culture. Furthermore, injecting 1BC linked to the CPP peptide into the left ventricle wall of mouse hearts results in uptake of the 1BC protein by resident cardiomyocytes. We are proposing further studies in both cell culture and animal models, to continue the development of this system and to test its performance in established cardiac models. The studies include assessing the ability of the delivery system to protect cells in culture from osmotic, reactive oxygen species and hypoxic stressors. We will also examine the ability of the system to deliver 1BC to hearts, in an ex vivo model, in a manner that provides protection from I/R. Lastly, we will examine the ability of the delivery system to deliver 1BC to cardiomyocytes within the infarct zone and protect the tissue from damage and cell death in an in vivo mouse model of MI. PUBLIC HEALTH RELEVANCE: Heart attacks are responsible for a significant number of deaths in the U.S. and are a major contributing factor to other forms of heart disease related death. The proposed research explores a new technique to introduce protective molecules directly in to the cells of the heart, with the goal of protecting the heart against damage caused by a heart attack.